<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title></title>
</head>
<body>
	<input type="button" name="" id="btn" value="click" style="width: 50px;height: 50px;background-color: red;font-size: 30px;">
	<script type="text/javascript">
		var btn = document.getElementById('btn');
		btn.onclick = function(){
			alert(btn.type);
			console.log(btn.type);

			btn.value = 'Peter';
			console.log(btn.style['font-size']);
			console.log(btn.style.fontSize);
		};
	</script>
</body>
</html>